The proposed project will investigate the dynamic expression of maladaptive personality traits in daily life in order to clarify the nature, variabilty, and predictors of dysfunctional behavior in a sample of patients with personality disorders (PDs) over a 100-day period. This work is timely given the serious consequences of personality pathology and PDs and the current focus on how best to conceptualize disordered personality. Consistent with modern conceptions of dimensional models of psychopathology, the proposed study focuses on pathology related to Antagonistic personality traits. Antagonistic traits include those such as hostility, aggression, manipulativeness, among others, are major components of Narcissistic, Antisocial, and Borderline PDs, and have been linked with behaviors such as sexual coercion, interpersonal violence, and suicide (behaviors that have severe real-world consequences). Thus, it is imperative that the nature of Antagonistic traits be well understood to inform assessment, diagnosis, and interventions. It is now widely recognized that personality pathology arises from the maladaptive expression of basic personality traits via the dynamic within- person processes and responses to day-to-day stressors in the environment. However, the dynamic maladaptive processes of PDs currently are understudied and poorly understood, despite the fact that they provide optimal targets for clinical interventions. The proposed study integrates current theory regarding personality, psychopathology, and individual differences, and applies novel design and statistical methodology to examine dynamic processes in the expression of Antagonistic traits in daily life. A more complete understanding of personality pathology requires a methodology that goes beyond traditional studies that rely on cross-sectional designs to examine dynamic changes and contextual factors that precipitate maladaptive responses and impairments in functioning. The use of intensive daily assessments and sophisticated multilevel models are essential for advancing our understanding of the expression of personality pathology. In this project, such modeling techniques will be applied to data collected using repeated daily assessments in the real world to examine processes associated with Antagonistic traits. Specifically, this study assesses patients with PDs on daily life experiences over the course of 100 days. Daily assessments of basic psychological variables (e.g., interpersonal behavior, emotions), stressors, and PD symptomatology will provide the necessary data to examine variability in and processes related to dysfunctional behavior, and the determinants of those processes. Results of the proposed study have implications for the assessment, diagnosis, and treatment of severe personality pathology. PUBLIC HEALTH RELEVANCE: Results of the proposed study have implications for the assessment, diagnosis, and treatment of severe personality disorders. The results will provide a much needed window in to the processes of antagonistic behavior (e.g., hostility, aggression), daily stress, and emotion in individuals diagnosed with personality disorders. Findings have the potential to identify treatment targets in the form of maladaptive cycles or processes.